Although Democratic candidates received a nationwide plurality of more than 1.4 million votes (1.2%) in all House elections,[6] the Republican Party won a 33-seat advantage in the state-apportioned totals, thus retaining its House majority by 17 seats. This disparity – common in close elections involving single-member district voting[7] – has on occasion been attributed to gerrymandering in the congressional redistricting process following the 2010 United States Census.[8][9][10] However, some analysts have argued that Republicans would have won the House even without taking into account the impact of gerrymandering.[11][12] An alternative explanation was that the large number of Democratic votes in urban centers led to "unintentional gerrymandering," as compact districts naturally led to "wasted votes" in districts that easily elected Democratic candidates.[11][13] The GOP also had a greater number of incumbents, who tend to have an advantage in elections.[13]

In the previous century, on four occasions the party with a plurality of the popular vote was unable to receive a majority in the House, but only twice since World War II.[10] The last times were in 1952 and 1996, in which the GOP held a majority in the House. The 1942 election was the last time that the Democrats held a majority in the House without winning the popular vote.[14]

Ten incumbent Democrats lost re-election; four to fellow Democrats and six to Republicans. Four losses were in California: two due to redistricting putting two incumbents together (resulting in a net loss of two for the Democrats) and two due to the state's "Top Two Primary." Two incumbents outside of California lost to Republican incumbents after being redistricted to the same district.

California retained its fifty-three seats: four new seats were created when four pairs of Representatives were redistricted to run against each other. An additional Republican incumbent, Gary Miller, won re-election in an entirely different district from the one he had previously represented.[61] The election featured the first use of the top-two primary system in which primary elections list candidates from all parties on one ballot, and the top two vote-getters advance to the general election. Two elections (30th and 44th districts) featured two Democratic incumbents running against each other.[62]

Florida gained two seats in reapportionment. As a result of the Fair Districts Amendment, approved by voters via referendum in 2010, the legislature could not take incumbency into account in drawing the lines.[63] As a result, two incumbent Republicans, John Mica and Sandy Adams, were drawn into the same district, creating a third new seat.[64]

Massachusetts lost one seat in reapportionment, forcing a pair of incumbent Democrats into the same district, although one, John Olver, retired in advance of the legislature's approval of new maps. Primary elections were held September 6, 2012.

Incumbent Thad McCotter (R) failed to make the ballot for renomination, and then resigned July 6, 2012.

Winner of the special election finished the term ending January 3, 2013.
Winner of the general election served the next term.
Republican hold: Incumbent was a Republican, interim Representative would be a Democrat, but successor would be a Republican.

New York lost two seats in reapportionment. After the legislature failed to reach agreement, New York conducted its 2012 congressional elections under a map drawn by a federal magistrate judge. Two incumbent Representatives saw their districts eliminated; one, Maurice Hinchey, chose to retire, while the other, Bob Turner, chose to run for the U.S. Senate.[68] A third incumbent impacted by redistricting, Gary Ackerman, chose to retire, creating an open seat.[69]

Texas gained four seats in reapportionment. After the initial redistricting map drawn by the Texas Legislature was denied pre-clearance by a federal district court under Section 5 of the Voting Rights Act, Texas conducted its 2012 congressional elections under a court-ordered interim map.[71]